1. Field of the Invention
Embodiments of the present invention generally relate to caulking guns.
2. Description of the Related Art
Generally, caulking guns are designed primarily for dispensing caulk packaged in a cylindrical container or cartridge. The cartridge has a dispensing nozzle on one end that dispenses caulk during a calking operation. The caulk is forced from the cartridge nozzle by forcing a movable wall end disposed within the cartridge toward the nozzle end. Conventionally, hand-held caulking guns use a piston type member, e.g., piston, driven by a shaft to push the movable wall. The piston member and shaft may be hand driven in a mechanical caulking gun as known. Unfortunately, such mechanical caulking guns during use often cause fatigue of the hand of the user thereby limiting the efficiency of the caulking operation. Further, due to varying levels of hand strength and gripping ability a user may apply a non-uniform hand-driven force thereby creating a non-uniform flow of caulk.
Electric caulking guns have been developed to help resolve such hand caulking issues by easing the work required by the user to move the movable wall end of the cartridge. Conventional electric caulking guns use a motor, such as a DC motor, in combination with a piston and shaft configured to apply force to the movable wall when a user activates the motor. Electric caulking guns are configured with a motion translation linkage that converts the motor rotation to linear piston motion. Some motion translation systems are designed to provide torque reduction to the motor so the motor size and therefore electrical energy consumption may be reduced. Unfortunately, such conventional motion transmission linkage is generally complicated thereby reducing the energy transmission between the motor rotation and the piston.
One type of transmission linkage is a single cam electric caulking gun. Such a single cam electric caulking gun uses a single cam motion to force the position forward while providing some torque reduction. Unfortunately, such a single cam only forces caulk forward when the cam is in a lifting portion of rotation and therefore provides no force to the piston during the cam return or retrograde portion of cam rotation to force the caulk forward. Such a change in caulking force causes a non-uniform flow of caulk from the cartridge.
Another type of transmission linkage is the screw type of linkage where the piston is rotatably coupled to a long screw on one end and the motor is coupled to the other end. While the screw provides an even caulking force when rotated, unfortunately, such a screw type of device requires a larger motor as little if any torque reduction may be derived therefrom. Conventionally gears are often used to provide such torque reduction. Unfortunately, gears add complexity and reduce the power transmission between the motor and piston. Moreover, a screw type linkage and gears increase the complexity of the portion of the apparatus dedicated to accommodating retraction of the piston for cartridge replacement.
Therefore, what is needed is a caulking gun that provides an even flow of caulk that is efficient to use, inexpensive to build and permits easy cartridge replacement.